import java.io.*;
import java.util.*;
import java.util.regex.*;

public class User {
    private String email;
    private String password;
    private String type; // 小学/初中/高中

    public User(String email, String password, String type) {
        this.email = email;
        this.password = password;
        this.type = type;
    }

    public String getEmail() { return email; }
    public String getType() { return type; }
    public boolean checkPassword(String pw) { return password.equals(pw); }
    public void setPassword(String pw) { password = pw; }

    // 文件保存
    public static void saveUsers(List<User> users, String filename) throws IOException {
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(filename));
        out.writeObject(users);
        out.close();
    }

    @SuppressWarnings("unchecked")
    public static List<User> loadUsers(String filename) {
        try {
            ObjectInputStream in = new ObjectInputStream(new FileInputStream(filename));
            List<User> users = (List<User>) in.readObject();
            in.close();
            return users;
        } catch (Exception e) {
            return new ArrayList<>();
        }
    }

    // 验证邮箱格式
    public static boolean validEmail(String email) {
        String regex = "^[\\w-\\.]+@[\\w-]+(\\.[\\w-]+)+$";
        return Pattern.matches(regex, email);
    }

    // 验证密码
    public static boolean validPassword(String pw) {
        if (pw.length() < 6 || pw.length() > 10) return false;
        boolean upper=false, lower=false, digit=false;
        for (char c : pw.toCharArray()) {
            if (Character.isUpperCase(c)) upper=true;
            if (Character.isLowerCase(c)) lower=true;
            if (Character.isDigit(c)) digit=true;
        }
        return upper && lower && digit;
    }
}